Nutritional Studies with the Clostridium botulinum Group

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Abstract
The factors which influence the initiation of growth from small inocula of Clostridium parabotulinum type A in the defined medium previously described were re-examined. CO2 was found essential for rapid and regular growth from small inocula; it could be partially replaced under conditions of strict CO2 depletion by an unidentified factor present in enzymic hydrolysate of casein or yeast extract. The growth requirements of the various serological types of C. botulinum group were studied and compared with those of C. parabotulinum type A. It was found that the various organisms can be classed into two nutritional groups: (a) those which gave rapid and heavy growth in a chemically defined medium as described for type A, with some variations in respect of vitamin requirements: here belong C. parabotulinum type A (12 strains tested), type B (9 strains) and C. sporogenes (10 strains); (b) organisms which failed to grow in the defined medium or in a partially-defined medium (containing acid hydrolysate of casein) supplemented with all known B-vitamins: this group comprised organisms of the type C (2 strains) type D (4 strains) and type E (5 strains, of which 3 grew in a partially defined medium). The similarity in nutritional requirements of Clostridium sporogenes to C. parabotulinum types A and B and the similarity in cultural and biochemical properties make C. sporogenes indistinguishable from, and perhaps identical with, non-toxigenic strains of C. parabotulinum types A and B.